期刊
ASTROPHYSICAL JOURNAL
卷 858, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.3847/1538-4357/aab8fe
关键词
stars: activity; stars: flare; stars: individual (2MASS J12321827-0951502, TRAPPIST-1)
资金
- NASA [NNX15AV64G, NNX16AE55G, NNX16AJ22G, NAS5-26555]
- National Science Foundation [AST-1614770, AST-1238877]
- NASA Office of Space Science [NNX09AF08G]
- NASA Science Mission directorate
- National Aeronautics and Space Administration [NNX08AR22G]
- NASA [NNX15AV64G, 796797, NNX16AJ22G, 903236, NNX16AE55G, 906061] Funding Source: Federal RePORTER
We report the white light flare rates for 10 ultracool dwarfs using Kepler K2 short-cadence data. Among our sample stars, two have spectral type M6, three are M7, three are M8, and two are L0. Most of our targets are old low-mass stars. We identify a total of 283 flares in all of the stars in our sample, with Kepler energies in the range log E-Kp similar to (29-33.5) erg. Using the maximum-likelihood method of line fitting, we find that the flare frequency distribution (FFD) for each star in our sample follows a power law with slope -alpha in the range -(1.3-2.0). We find that cooler objects tend to have shallower slopes. For some of our targets, the FFD follows either a broken power law, or a power law with an exponential cutoff. For the L0 dwarf 2MASS J12321827-0951502, we find a very shallow slope (- alpha = -1.3) in the Kepler energy range (0.82-130) x 10(3) erg: this L0 dwarf has flare rates which are comparable to those of high-energy flares in stars of earlier spectral types. In addition, we report photometry of two superflares: one on the L0 dwarf 2MASS J12321827-0951502 and another on the M7 dwarf 2MASS J08352366+1029318. In the case of 2MASS J12321827-0951502, we report a flare brightening by a factor of similar to 144 relative to the quiescent photospheric level. Likewise, for 2MASS J08352366+1029318, we report a flare brightening by a factor of similar to 60 relative to the quiescent photospheric level. These two superflares have bolometric (ultraviolet/optical/infrared) energies 3.6 x 10(33) erg and 8.9 x 10(33) erg respectively, while the full width half maximum timescales are very short, similar to 2 min. We find that the M8 star TRAPPIST-1 is more active than the M8.5 dwarf 2M03264453+1919309, but less active than another M8 dwarf (2M12215066-0843197).
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据